Phase/Pwm?

MegaHurtz · 28 May 2009

Your one of the folk that can`t hear phase changes. no biggie:D

NekroDisko · 3 Jun 2009

Well, if you cant really hear the changes, try using a scope after the oscillator, then you can see the changes. The whole wave will obviously change as it plays, but when you turn the phase-knob you will see the wave glide to the left or right,depending on what value-range the knob is assigned to. AFAIC a knob with equal negative and positive values is preferable. The same goes with the Pwm-knob, but this knob will only affect one of the Saw-oscillators (the inverted one preferably) inside the Square-oscillator.

Hope this may help you out. 🙂

A Uio · 30 Jun 2009

This might be helpful

http://en.wikipedia.org/wiki/Phase_(waves)

I'm not that knowledgeable, but I believe the only way to hear phase changes is when you change the phase of one wave relative to another. For example, two sine waves that are in phase will simply add in volume/amplitude. If they are exactly out of phase, they will work to cancel each other out. Anywhere in between will generate a more complex sound.

Cheers, A

NekroDisko · 4 May 2010

For example, two sine waves that are in phase will simply add in volume/amplitude. If they are exactly out of phase, they will work to cancel each other out. Anywhere in between will generate a more complex sound.

Yes, you are quite right! This is also a problem posed when audio-mixing for example two identical guitar-tracks in false-stereo (a mono guitar-track(panned left) being copied to another track (panned right) resulting in signal cancellations). This works the other way around (as even a clean guitar-sound isnt a sine-wave until its sustain-level AFAIK).

In short, to hear the difference of a sounds phase you must have 2 sources of sounds to compare between.

PWM though is a different matter (however not un-related). Pulse Width Modulation basically requires a Saw-waveform and its direct opposite (the inverted Saw-waveform known as a Ramp-waveform). These two waveforms played together,and simultaneously will create a Pulse- or Square-waveform. Now, if you alter the phase of one of the included waveforms(usually the inverted one), the "pulse" or "square" will be shortened or elongated, because of one of the sound-sources (oscillators)drifting more out of phase from the other one.

This will result in a "thinner" or "wider" sound relative to how close the 2 waveforms phase are in relation to eachother.

I hope I made myself clear here (still, this is my own understanding of the Phase and PWM conundrum which is being expanded by every year). But this is the basics AFAIK. Cheers 🙂

Acrobat · 6 May 2010

jps39 wrote: I can not hear any real difference in the sound of the synth with phase knob turned on full or not.

No, seriously, if you smoke a lot, you probably will... 😉 😇

trogluddite · 6 May 2010

jps39 wrote: trying out the Phase via Knob

If you move the phase with a knob, all you are really doing is shifting the wave back and forth in time slightly - but your ears hear just the pitch of the oscillator, not the time delay. (You might just hear the note go slightly sharp or flat as you move the control) As nekrodisco says, phase is something you can't judge in isolation, you need more than one sound source. But changing phase with a knob still means that the tone is fixed by the knob position, which doesn't sound too interesting.

To really bring it to life, try connecting the phase input to an LFO or envelope generator - it's when the phase is changing that you will really start to hear the effect.